This invention relates generally to the field of downhole tools in a wellbore, more particularly to a downhole tool attachment mechanism and method via the application of magnetic fields.
In the course of completing an oil and/or gas well, a wellbore is drilled from the earth's surface into a subterranean production zone. Often included in the downhole apparatus are a variety of tools to perform tasks associated with drilling, completion, and maintenance of the wellbore. For example, downhole sensors may be attached to a wellbore to measure various wellbore and subterranean formation parameters including, but not limited to, pressure, temperature, resistivity, and/or porosity. The measurement results may provide important information for an operator on the surface of a rig site to make field-development decisions.
One approach of downhole tool deployment is to attach one or more downhole tools to a wellbore tubular at the surface, and then lower both into the subterranean wellbore together. In this case, once deployed to an appropriate depth, the downhole tools usually remain in the wellbore while the production string remains in the wellbore. They may then be detached or removed from the wellbore when the tubular and/or casing is retrieved to surface.
Alternatively, during drilling and/or maintenance of a well, downhole tools may be deployed into the well via a length of slickline, wireline and/or coiled tubing which is controlled from the surface. For the downhole tool to perform its designed function, it needs to be positioned in the well at an appropriate depth. Following positioning, the downhole tool is then actuated by one of several methods, depending on the type of downhole tool. In this case, the downhole tool is usually raised back to surface after completion of its planned function.